The present invention relates generally to a sling arrangement carried by a prime mover for securement to a load and one for rapid load discharge and sling disengagement at a discharge site both of the latter without the aid of ground attendants.
Aerial transport of logs by helicopter has now become commonplace by reason of the savings realized primarily in the avoidance of road building costs especially in areas of rough terrain. Further, airlifting avoids environmental damage to forests heretofore caused by logging vehicles and related equipment. More recently helicopters have proved to be highly suitable for the harvesting of Christmas trees where the trees are grown on a large commercial scale.
In use presently are elongate, fabricated slings which ground attendants must wrap about the sizable bundle of collected trees weighing several hundreds of pounds. The tree bundle is then airlifted to a discharge site whereat the sling must be manually removed from the deposited tree bundle. As the bundles are several hundreds of pounds in wight and several feet in height, the matter of manually extracting the sling from about the bundle is extremely arduous and time consuming. Accordingly, to prevent airlifting operations from being paced by the availability of slings it has heretofore been the practice for the helicopter contractor to use several of the costly slings and several attendant crews at any one airlifting operation. This practice is extremely costly as each sling represents a sizable investment. Additionally, the difficult task of separating slings from the tree bundle requires several crews of support workers to remove same, roll the slings and carry same back to the tree harvesting site, the latter contributing to a high labor expense.
A still further drawback to known slings is the use of wooden spreaders of block shape at intervals along the parallel sling lines. The spreaders render sling retraction from beneath a tree bundle difficult in view of the spreaders tending to hang-up on tree branches and tree trunks.